Given a number x, Find y (y > 0) such that x*y + 1 is not a prime.
Examples:
Input : 2 Output : 4 Input : 5 Output : 3
Observation:
x*(x-2) + 1 = (x-1)^2 which is not a prime.
Approach:
For x > 2, y will be x-2 otherwise y will be x+2
C++
#include <bits/stdc++.h>using namespace std;int findY(int x){ if (x > 2) return x - 2; return x + 2;}// Driver codeint main(){ int x = 5; cout << findY(x); return 0;} |
C
#include <stdio.h>int findY(int x){ if (x > 2) return x - 2; return x + 2;} // Driver codeint main(){ int x = 5; printf("%d",findY(x)); return 0;} |
Java
// JAVA implementation of above approachimport java.util.*;class GFG{ public static int findY(int x) { if (x > 2) return x - 2; return x + 2; } // Driver code public static void main(String [] args) { int x = 5; System.out.println(findY(x)); } }// This code is contributed// by ihritik |
Python3
# Python3 implementation of above # approachdef findY(x): if (x > 2): return x - 2 return x + 2# Driver codeif __name__=='__main__': x = 5 print(findY(x))# This code is contributed# by ihritik |
C#
// C# implementation of above approachusing System;class GFG{public static int findY(int x){ if (x > 2) return x - 2; return x + 2;}// Driver codepublic static void Main(){ int x = 5; Console.WriteLine(findY(x));}}// This code is contributed// by Subhadeep |
PHP
<?php// PHP implementation of above approachfunction findY($x) { if ($x > 2) return $x - 2; return $x + 2; } // Driver code $x = 5; echo (findY($x)); // This code is contributed// by Shivi_Aggarwal?> |
Javascript
<script>// JavaScript implementation of above approach// Function to check whether it is possible// or not to move from (0, 0) to (x, y)// in exactly n stepsfunction findY(x){ if (x > 2) return x - 2; return x + 2;}// Driver codevar x = 5;document.write(findY(x));// This code is contributed by Ankita saini</script> |
Output:
3
Time Complexity: O(1)
Auxiliary Space: O(1)
